First-principles studies on magnetism of Ni clusters coated and alloyed with Pd

First-principles electronic-structure calculations are performed for the Ni clusters coated and alloyed with Pd. For coated clusters, the magnetic mom ents of the Ni core are reduced as compared to the bared one. Especially, N i1Ni12Pd6Pd24Pd12 cluster with O-h symmetry consists of the ferromagnetic N i core, the ferromagnetic Pd and paramagnetic Pd shells, the induced magnet ic moment of Pd in the interface is 0.1 mu(B), qualitatively in agreement w ith experimental results found in Ni particles coated with Pd. The dependen ce of magnetic moment on Pd thickness displays an oscillatory behavior, sim ilar to that found in Co clusters coated with Cu or Ag and in Ni/Pd multila yers. For the alloyed clusters, the enhanced magnetism is confirmed, and th e mechanism is clarified: which is resulted not only due to the large atomi c distance of Pd but also due to electron transfers. The explanations are g iven for the different magnetic behaviors between coated and alloyed cluste rs. (C) 2000 Published by Elsevier Science B.V. All rights reserved.